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g
D
e
. s
e
s
r
Characters
0-9,#,*
I
p
W
Low-Level Modem Command Dictionary
Meaning
Digi ts to be dialed.
The following digits, until the next P or W, should be dialed using
interrupt (pulse) dialing. The I should be preceded by a P if you
want the modem to detect no dial tone and report the NO DIAL
response.
Wait for dial tone, then resume dialing using adaptive dialing. If no
dial tone is detected within the timeout, the dial command will be
aborted, and the NO DIAL response will be reported. The dial string
will be executed as if the first character was a P unless it has a P or
W as its first character.
The timeout is 3 s for an implied P, and 4. 5 s for a P that actually
appears in the dial string.
These times consist of a 2 s delay,
followed by detection of a continuous dial tone for the remainder of
the timeout.
Wait for 5 s, then resume dialing next part of string using tones.
After the modem dials, it begins to look for a busy signal or a ring. The modem response depends on the
mode it was in when dialing commenced. If the modem was in VOICE mode, it waits until it determines
that the line is not busy, then responds with CONNECT. It may respond with RING first. Then the modem
will remain off-hook regardless of the status of the called phone (which will continue to ring). If the line
is busy, the modem goes on - hook and responds with
BUSY.
If the modem is in MODEM mode, it dials as above, then continues to monitor the status of the line. If a
busy signal is detected, it hangs up and responds with
BUSY.
If
a carrier is detected, the modem enters
ORIGINATE mode. The behavior at this point is as if the 0 (ORIGINATE) command was executed. See
the 0 command for details.
If command echoing is enabled
(E
0), the modem will echo the dial string when it receives the command
string containing it. The dial string will be echoed in exactly the same form as it appeared in the
command string. The modem will echo the dial string again each time it is dialed by any of the three
dialing commands. The
D
and X commands echo the string once (unless they are repeated in the command
string--flee below). The R command echoes it up to 10 times as it redia Is.
The dial string echoed during dialing will be in a different form than m the command string. Characters
that are ignored in the dial string are not echoed. The special characters P and
W
will not be echoed, but
will break the dial string into segments separated by spaces. Echoing will stop for the duration of the
waits imposed by those characters. The special character I will not be echoed, but will cause all digits
between the I and the next P or
W
(or the end of the dial string) to be echoed. The digits
#
and
*
will be
echoed as ; and
<.
There will be a trailing space but no carriage return or line feed after the entire dial
string has been echoed .
A low-level command string can contain multiple dialing commands, but it probably will not have the
behavior you expect. All the dialing commands are counted, and their dial strings are concatenated
together. If the dialing operation results in a
BUSY
response, the operation will be repeated for the
number of times that there are dialing commands, up to a maximum of ten times per command (D, R, or
X).
Because X depends on VOICE or MODEM mode, and only partially checks line status, multiple X
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